At the bottom of the shaft, was a room with the opening to the tunnel itself. A sort of mezanine was above where officials said the marijuana was stored and lowered down as it was shipped north.
— John Gibbins / John Gibbins/Union-Tribune

Mexican Army General Gilberto Landeros answered questions from the media at a press conference. Behind him were the dimensions of the tunnel and the amount of marijuana recovered on the Mexican side.
— John Gibbins / John Gibbins/Union-Tribune

A six-month investigation into what authorities described Wednesday as the most sophisticated drug tunnel ever found beneath the California-Mexico border has resulted in six arrests and a record confiscation of more than 32 tons of marijuana.

The passageway, which dropped to 40 feet below ground and was 612 yards long, connected warehouses in Tijuana and Otay Mesa. It had an electric rail system, an elevator and walls shored up with wood.

The operation by U.S. and Mexican law enforcement marked the second major tunnel discovery in a two-week period. It comes almost a year after the uncovering of two other major illicit cross-border passageways and related marijuana seizures.

Members of the San Diego Tunnel Task Force said the discoveries have followed a seasonal trend in recent years, with significant seizures taking place in the latter months of the year.

Authorities “believe this coincides with the increase in inventory in Mexico due to the harvest season,” said Derek Benner, special agent in charge of U.S. Immigration and Customs Enforcement in San Diego.

Benner said the investigation of the latest tunnel began in May, when authorities first learned of a tunnel possibly under construction in an Otay Mesa warehouse. The passageway was barely completed when law enforcement closed in this week, he said.

The tunnel “took massive resources and massive amounts of time to construct and plan and build, and we were able to shut it down before it became operational,” Benner said at a news conference.

This week’s 32.4-ton marijuana seizure was the largest confiscation associated with a single tunnel, Benner said. Its estimated street value is $65 million.

Most of the marijuana — about 20 tons — was found at the unmarked Hernandez Produce Warehouse, inside what appears to be a largely unoccupied industrial building on Calle de Linea near the international border fence.

In Tijuana, Mexican soldiers seized nearly four tons at the tunnel’s entrance beneath the tiled floor of an unmarked warehouse near the A.L. Rodríguez International Airport. More than 10 tons were seized from a tractor-trailer driven from the Otay Mesa warehouse to the City of Industry outside Los Angeles.

Agents with the Tunnel Task Force received information that Hernandez Produce Warehouse “possibly contained a subterranean, cross-border tunnel,” according to a complaint filed by the U.S. Attorney’s Office in San Diego.

U.S. Attorney Laura Duffy said her office is pressing charges against two suspects, Salvador Zuniga and Laureano Gonzalez, who were arrested Tuesday after allegedly driving the truck to the City of Industry. If found guilty of conspiracy and distribution charges, both would face at least 10 years in prison, Duffy said.

Four other suspects connected to the seizure were arrested at the City of Industry warehouse, and they face similar charges in California’s Central District. They were identified as Saul Perez, Adrian Escobedo, Samuel Treto Jr. and Miguel Angel Felix Echavarria.

Authorities said drug tunnels have become more common in recent years along the San Diego-Tijuana border because traffickers have found it harder to smuggle drugs amid greater U.S. enforcement. “If they can’t cross the border above ground, they attempt to tunnel underneath it,” Duffy said.